This invention pertains to an apparatus and method for converting color image data for display on a display screen to color image data for printing on a color printer. This application claims the foreign priority benefits of Japanese Application No. 2-273508 which was filed on Oct. 15, 1990. This Japanese application and its translation are wholly incorporated by reference herein.
The background color for a color display screen is usually selected such that it will contrast with the color or colors of the image to be displayed on the screen. When that same image is printed on a color printer, however, the shape of the image may be ill defined if the color of the paper is used as the background, and one of the colors of the image is substantially identical to the color of the paper. This is particularly true if an area at the boundary of the image is substantially identical to the color of the paper.
It is well known to print an image and its background exactly as they appear on a display screen, such that a black background on the screen prints out as a black background on the paper. However, if the background is not printed such that the background takes on the same color as the paper, the printed image usually creates a similar, but different impression as the same image displayed on the screen.
It is also well known to print white areas on a display screen as black areas on the paper, and to not print a black area on display screen. Thus, when using white paper, the image on the display screen is inverted, such that black prints out as white, and white prints out as black. In this method, however, a white image, such as the white bird of FIG. 13, is printed as a black bird on the paper. Thus, this method results in a printed image that differs substantially from the image that's displayed on the screen.
Accordingly, the invention described below provides a means for converting image data representing a white area on the screen (or other color that's the same color as the printer paper) into image data for printing an outline of the white area.